Store function type and expose it with `subr-type'

Store function type and expose it with `subr-type'

	* src/lisp.h (struct Lisp_Subr): Add 'type' field.
	(SUBR_TYPE): New inline accessor.
	* src/pdumper.c (dump_subr): Update for 'type' field.
	* src/data.c (Fsubr_type): New primitive.
	(syms_of_data): Update.
	* src/comp.c (ABI_VERSION): Bump new ABI version.
	(make_subr): Set type.
	(Fcomp__register_lambda, Fcomp__register_subr)
	(Fcomp__late_register_subr): Receive and pass subr type to
	'make_subr'.
	* src/alloc.c (mark_object): Mark subr type.
	* lisp/emacs-lisp/comp.el (comp-func): Change slot type into mvar.
	(comp-emit-for-top-level, comp-emit-lambda-for-top-level): Pass
	type mvar to subr register functions.
	(comp-compute-function-type): Fix-up subr type mvars.
	* test/src/comp-tests.el (comp-tests-check-ret-type-spec): Use
	`subr-type'.